Abstract Previous research established growth-stage-specific irrigation scheduling for upland cotton (Gossypium hirsutum L.) in Uzbekistan. We report further investigation of irrigation scheduling for two cotton varieties and its effect on seed-lint yield and irrigation crop water productivity with and without use of a wetting front detector (WFD) to trigger irrigation cessation. A WFD is a device buried in the soil to sense when the wetting front from irrigation reaches a certain depth. The depth may be adjusted upon installation of the WFD. Field trials were conducted in silt loam soil near Tashkent, Uzbekistan, in 2016, 2017, and 2018. The growth stages of germination to flowering, flowering to boll formation, and maturation were considered for the development of irrigation scheduling regimes with respect to field capacity water content (Fc). The best growth, development and seed-lint yield for the Sultan cotton variety were achieved with irrigations scheduled at soil water content levels of 70%, 75%, and 65% of Fc during the aforementioned three growth stages, respectively, and were achieved for variety UzPITI-103 with irrigations scheduled at 70%, 70%, and 60% of Fc during the aforementioned plant growth stages, respectively. There were appreciable varietal differences in water requirement with the early maturing Sultan variety having a larger water requirement. In contrast, irrigation scheduling with larger Fc values did not result in increasing the yield for the UzPITI-103 cotton variety. In comparison with irrigation without WFD, the use of the WFD decreased irrigation duration by 2.0–3.5 h, net irrigation amount by 7–90 m3 ha−1, irrigation run off by 69–134 m3 ha−1, and deep percolation below the root zone by 10–17 m3 ha−1, while increasing irrigation crop water productivity by 0.08–0.10 kg m−3 and seed-lint yield by 0.04–0.10 Mg ha−1. Irrigation scheduling regimes based on percentages of Fc and irrigation with WFD should be considered applicable practices for upland cotton varieties on silt loam soils of the central zone of Uzbekistan and for similar soil-climatic conditions of Central Asian countries.

中文翻译：

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在乌兹别克斯坦使用湿前探测器改进棉花灌溉计划

摘要 先前的研究确定了乌兹别克斯坦陆地棉 (Gossypium hirsutum L.) 生长阶段特定的灌溉计划。我们报告了对两个棉花品种的灌溉调度的进一步调查，及其在使用和不使用湿润前沿检测器 (WFD) 触发灌溉停止的情况下对皮棉产量和灌溉作物水分生产力的影响。WFD 是一种埋在土壤中的装置，用于感应灌溉的湿润锋何时达到一定深度。安装 WFD 时可以调整深度。田间试验于 2016 年、2017 年和 2018 年在乌兹别克斯坦塔什干附近的粉砂壤土中进行。 萌发到开花、开花到成铃和成熟的生长阶段被考虑用于制定与田间容量相关的灌溉调度制度水含量（Fc）。苏丹棉品种的最佳生长、发育和皮棉产量是在上述三个生长阶段分别以 Fc 的 70%、75% 和 65% 的土壤含水量进行灌溉的情况下实现的。品种 UzPITI-103，在上述植物生长阶段分别按照 Fc 的 70%、70% 和 60% 进行灌溉。不同品种的需水量存在明显差异，早熟的苏丹品种需水量较大。相比之下，具有较大 Fc 值的灌溉计划不会导致 UzPITI-103 棉花品种的产量增加。与不使用 WFD 的灌溉相比，使用 WFD 的灌溉时间减少了 2.0-3.5 h，净灌溉量减少了 7-90 m3 ha-1，灌溉径流减少了 69-134 m3 ha-1，根区以下深度渗透 10-17 m3 ha-1，同时将灌溉作物的水生产力提高 0.08-0.10 kg m-3，种子皮棉产量提高 0.04-0.10 Mg ha-1。基于 Fc 百分比的灌溉调度制度和 WFD 灌溉应被视为适用于乌兹别克斯坦中部地区粉壤土上的陆地棉品种和中亚国家类似土壤气候条件的做法。